A tent is the most standard form of shelter used by hikers and backpackers. It can be made of a variety of materials and comes in all shapes and sizes.
Freestanding vs. Non Freestanding
A freestanding tent is one that can stand on it's own without needing to be staked into the ground. These tents require tent poles to stand, either by being inserted through loops attached to the fabric of the tent, or being clipped on afterwards. A non freestanding tent is often supported by trekking poles or something similar, with guy lines being staked into the ground creating tension that keeps the tent standing throughout wind or other weather.
Materials
There are many types of tents, but most modern hiking tents will be made of either canvas, polyester, Nylon, or DCF (Dyneema Cuben Fiber). The type of material used for a tent will vary greatly depending on the need for the tent. For example, DCF is used most commonly in ultralight, single-walled tents, while cheaper and more durable tents will generally come in nylon or polyester.
Single-Walled vs. Double-Walled
A single-walled tent refers to a waterproof tent that only has one layer of material protecting the hiker from the elements. These tents are typically lighter than their double-walled counterparts, with the drawback being that condensation will be more of an issue. A double-walled tent is often what most think of when thinking of a traditional camping tent, which means that there is a main tent fabric that comprises the main structure of the tent, which is usually made of mesh for ventilation. That inner mesh wall will be accompanied by a separate fabric known as a rain-fly, which is water proof (or at least water resistant) which will have to be attached separately, but will protect from the rain. The benefit of the double walled is more versatility - for example, if the hiker is confident that it will not rain, they can forego the rainfly for cooler sleeping conditions, and even stargazing. However, because there is more fabric and poles involved in a double-walled tent, the drawback to this setup will be an increase in weight and carrying volume within the backpack.
Capacity
Tents are generally sold in a "per person" capacity, meaning as a 1 person tent, 2 person tent, 3 person tent, etc. These specifications are not standardized and in practice, most hikers find that the reality of the tent will better accommodate one less person than advertised. So while a 1 person tent may technically fit two people with very slim sleeping pads, in practice a single person will be most comfortable in a 2 person tent. This is especially true for thru-hikers who are living in their tents for months at a time and have more equipment to bring with them and manage.
